2 Networks + 1 Internet = Static Routing?

First, I would like to thank TPTB on linksysinfo for providing such a valuable resource. I have spent many a day lurking here and finding valuable information pertinent to our business' Linksys equipment.

That being said, I think I am encountering a problem slightly above my pay grade that you all may be able to help mentor me in.

Currently, I oversee the network administration tasks of 2 separate companies owned by the same principals located in the same building. To date, the networks have remained independent from one another. The main snowboard distribution company has two T1's bonded for their internet access. The nutritional supplement company has a DIA for voice and data.

Next week, a new voice and data solution will be activated that will provide us with substantially more bandwidth. The provider has provided me with all of the information for the new connection, and they will terminate to a cable that should be plugged into a router.

The problem is that now that we are handling a single, unified connection, I obviously have to place a piece of network equipment at the feed to parse off bandwidth and ensure that things like real time inventory and order imports work correctly for one while things like Exchange work properly for the other.

If I am not mistaken, the best course of action would be to set up a router and use static routing to route transmissions to each respective network. However, I want to be ABSOLUTELY CLEAR that I am going about this the right way before I do any testing here. I am terrified that I am going to nuke our entire network, and this isn't something I have ever encountered short of studying it in a freaking book.

So here is my plan. Please tell me if I am being stupid about it, doing it wrong, or if there is a better practice for this that I am not currently pursuing:

I have a second RV016 (dubbed RV016-b from here on out). This router goes between the existing firewalls and the new Internet connection. This router should be switched to Router only in advanced options, and static routes created.

Therein lies the problem.

How exactly do I go about configuring this? Assuming that the Handoff info from the telco is:

Both Firewall gateways should plug directly into LAN ports on the router, correct?

Would the Vitamins router and the Boardshop router both be configured to access the External WAN as if the router wasn't even there?

Access rules, port forwarding, everything like that would all still apply, correct?

Are there any issues that we could expect to encounter in this situation?

Are there additional settings on the Router (RV016-b) that I should be concerned with?

I apologize for the noobishness of this question...I just have never dealt with this substantial of a networking issue before. I hope my concept of the fundamentals is correct in this situation, but I don't want my lack of confidence or any errors in my judgment to cost the company and substantial amount of down time.

Any help or input you all can provide me with would be greatly appreciated. All feedback is welcome!

Are you changing the internet access provider? In such a case the WAN address space will not remain the same as they were with other providers.

Also the router you want to be set as the static route rules is plugged to the WAN ports of the gateways. So the rules can not use the LAN adreeses of the gateways.

You should provide more informations about the old and the new internet connection service. Especialy important is if any of your clients do have own Internet IP assigned, or they are simply behind provider NAT.

so wait, are you basically replacing the individual internet connections with one connection that you plan to share?

and then do you want the 2 local networks to be able to see each other or you want to keep them both totally separate?

and are the 2 current connections coming from the same provider (both from verizon for instance) or are they from different providers (one is verizon and the other is comcast)? and is the new connection from from the same provider or from a totally different provider? if they're all from the same provider, you have a chance of keeping the same WAN IPs. If not, the new provider will assign a block of IPs to you and then you need to go into your domain registrar and update them with the new IPs...

and can you give us an estimate of how many clients and servers are on each network, if all of their mail and web services are hosted in house, etc.